There are many ways to increase the DC- DC converters. Including the use of inductors, which can be coupled as a transformer to increase voltage converters DC / DC non-isolated act by Lstfadh capacitors and other methods.

The high gain DC -DC converter with coupling inductor is used.  To achieve high voltage output gain, theconverter output terminal and boost output terminal are connected  serially with the coupled  inductor .

Ideally, try to reconcile the duty cycle to the value 1.

in practice if it exceeds 0.6 this is a great gain.

just increase the duty cycle in such a way that  L>=D(1-D)^2R/2f condition should meet where L is your applied inductance.

i think you can increase the gain to large values by increasing the duty cycle but you will need to reduce the switching frequency to keep the time you need for switching on and off process over the limits mentioned in the data sheet of the IGBT used in your chooper.

But here is the problem you will need large filters for this process.

Really i advise you to use multi step of your converter, it is better from the side of cost.

Increase gain by adding voltage multiplier at load side or use switch inductor at inductor place or use both so gain will be more than normal boost converter.

For achieving that one possibility is to use coupled inductors with an interleaved PWM. In addittion, this inductor will enhance the transient response of the converter.

You have more than 1 way to do it. You may (i) add a coupled inductor, (ii) add a voltage doubler network (essentially a diode-capacitor pair), (iii) use a voltage multiplier cell, (iv) use switched capacitor network or (v) use combinations of the above suggested methods judiciously. But the key lies in taking care of the power transfer capability also.

You have stated that you have designed the boost converter and now wish to increase the gain without changing the converter parameters. To increase gain, you need to increase the Duty Cycle, but values higher than about 0.8 will be difficult to achieve due to system instability as the gain increases very rapidly with small increase in duty cycle. Further, increase of Duty cycle will lead to increase of ON-time and hence increased peak-to-peak ripple in inductor current and increased output voltage ripple. To get same as earlier performance with same inductor, now you have to increase frequency such that actual ON-time is again same as earlier with increased duty cycle, hence current ripple & voltage ripple will remain same.

From theory the boost converter can achieve higher voltage gain, however, the voltage gain of a real boost converter is limited around 10. This is due to the fact that, the voltage gain has a dependence of the power losses. Then, we can identify a maximum value of the converter voltage gain for a set of converter parameters (switching frequency, ESR on inductor and capacitor, voltage droop in the diode and Ron in the MOSFET). That maximum value of voltage gain corresponds to a given duty cycle which we can consider the limit for stability. If we can reduce the power losses (conduction and switching), the maximum voltage gain and the corresponding duty cycle increase.

There are many ways to increase the DC- DC converters. Including the use of inductors, which can be coupled as a transformer to increase voltage converters DC / DC non-isolated act by Lstfadh capacitors and other methods.

Gain of DC to DC converter can be increased by varing Duty Cycle. One more method i think is cascading of Boost Converters.

By varying the Duty Cycle

By increasing the L values

You can use a multiplication circuit to increase the output voltage of your boost converter. It consists of rectifiers and capacitors. From 24VDC/1.4A you can reach 250VDC/0.1A for example, if you need a high voltage and a modest current. You still need just one active element (mosfet or similar) and a PWM controller circuit. Please remember to filter out any electric noise from the circuit so it does not spread to the supply or load circuits along the wires.

By increasing  duty cycle. i.e. using a PWM modulator.

Max. voltage gain of the boost converter is limited to 5.

if you model the effect of the parasitic elements of the converter in modeling of the system, you can find that the max. gain is limited.

however, you can increase the gain by using "high gain dc-dc converters"

e.g. switched inductor dc-dc converters

good luck

Actually, it is possible to use transformers or switched inductances, among others, "but without changing the converter parameters". As I understand, it means that input and output characteristics should not be changed.

ok. you are right.

the converter duty cycle must be changed any way

There are several methods to do so. it's true that we can increase the gain by varying the duty cycle ,increasing inductor size .we can also use voltage doubler circuit or coupled inductor for this purpose

There are different strategies of increasing gain. Most effective one, I assume is to control the duty cycle. But that may increase the THD which is not accepted at all. You can also reduce the switching losses by introducing ZVC and or ZCS. However power factor is another concern. So, you should coordinate all the three factors i.e. PF, THD and Efficiency. Variable switching frequency with variable duty cycle can be incorporate together, I guess.

Design of L and Duty cycle play a vital role

if you increase the converter duty cycle, voltage gain of the converter will be increased.

if you have designed the parameters, you must improve elements structure and design.

for example, if equivalent series resistances of the inductor and capacitor is reduced, the maximum accessible gain will be increased.

Also, you can employ low voltage switches and diodes.

however, in the standard boost dc-dc converter, maximum voltage gain is limited to 4-5.

if more voltage gain is required, you can use other dc-dc boost topologies like Switched Inductor DC-DC boost converter.

good luck

I suggest DC DC Multilevel Converter is best Suitable.

http://ieeexplore.ieee.org/Xplore/defdeny.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fstamp%2Fstamp.jsp%3Ftp%3D%26arnumber%3D6804492%26userType%3Dinst&denyReason=-133&arnumber=6804492&productsMatched=null&userType=inst

use this also

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=7054955&searchWithin=%22Authors%22:.QT.Mahajan%20Sagar%20Bhaskar%20Ranjana.QT.&newsearch=true

2.

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6924159&searchWithin=%22Authors%22:.QT.Mahajan%20Sagar%20Bhaskar%20Ranjana.QT.&newsearch=true